With accent marks:
Кто о чём, а вши́вый о ба́не.
Who is talking about what, and a lousy one about the bath.
This saying describes a situation when in a conversation of several people, one of them always talks only about what worries him. Even if the discussion is about a completely different thing. In the saying, such a person is compared to a "lousy one talking about the bath". Because until he bathes, and until this does not ease his suffering from the lice biting him, he will not care about anything else.
You can use this saying when someone always falls back on talking about the same thing.
Other Russian proverbs
We don't appreciate what we have but we cry when we lose it.
Live for a century, learn for a century, but die being a fool anyway.
Beast runs towards the hunter.
Do not chop the branch you sit on
Eggs don't teach the chicken.
Each sandpiper praises its swamp.
Being a guest is good, but being at home is better.
If I knew where I would fall, I would lay some straw there.